Single-phase motor.



E. F. W. ALEXANDERSON.

SINGLE PHASE MOTOB. APPLICATION FILED SEPT. 2, 1909.

1,021,289. Patented Mar. 26, 1912. j

Fig. I.

Q' MA HZZTNESEEB' INSZENTUR Y W \k @9 E ERNST rwjl'zrmnzzasmsz UNITED STATES PATENT OFFICE.

ERNST I. W. ALEXANDERSON, OF SGHENEGTADY, NEW YORK, ASSIGNOIR. T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SINGLE-PHASE MOTOR.

Specification of I ttcrs Patent.

Patented Mar. 26, 1912.

Application filed September 2, 1909. SerialNo. 515,771.

To all whom it may concern:

Be it known that I, Enn'sr F. W. ALEX- ANDERSON, a citizen of the United States, residing at- Schenectady, in the county of Schenectady and State of New York, have invented certain new and useful Improve ments in Single-Phase Motors,of which the following is a specification.

My invention relates to single phase motors of the'comnfiutator type. in which an inducing winding is placed on the stator and two circuits are closed through the rotor winding displaced from each other approxi mately 90 electrical degrees. The speed of such a motor may be controlled by varying the voltage on one set of brushes, the speed being substantially constant for any given value of voltage impressed on. the brushes, and the power factor of the motor may be controlledby impressing a variable voltage on the other set of brushes.

The object of my invention is to improve the operation and control of motors of this type and consists in a novel arrangement for obtaining upon the brushes the variable values ofvoltage for controlling the speed and improving the power factor of such motors. The further novelties of my invention are pointed out with more particularity in the claims annexed to and made a part of this specification.

My invention will best be understood by reference to the accompanying drawing in which- Figure 1 shows diagrammatically a motor arranged for control in accordancewith my invention, and Fig. 2 shows diagrammatically the arrangement of the controlling switch.

In the drawing A represents the inducing Winding on the stator and B the rotor Winding, which is provided with two sets of commutator brushes. One set of brushes 5 b is displaced by a small angle from the line of magnetization of the inducing winding, while the second set of brushes ?2 b is displaced approximately 90 electrical de grees from the first set.

C represents the primary, and G the secondary of a transformer for supplying current to the motor.

0 represents an auxiliary seco dary wind ing, and a represents an auxiliary winding on the stator of the motor in inductive relation to the inducing winding A. The left...

hand terminal of winding A and the righthand brush 7) are connected to fixed points on the secondary winding C. The other terminal of winding A and the left-hand brush 5 are connected to the contact adapted to make connections to diiferent points on the secondary winding C. By

moving the contact d the motor speed is controlled by impressing a variable voltage across the brushes 1) b. Atstarting the contact d is in such a position, with respect to the connect-ion to the right-hand brush b, that the voltage -in1pressed on the brushes 7) b is in opposition to the voltage induced in the rotor winding between these brushes by the inducing winding. To increase the motor speed the contact at is moved so as first to reduce the voltage impressed on the brushes Z2 6, then to short-circuit these brushes at about synchronous speed, and then to impress on the brushesa voltage in the opposite direction for operation above synchronism. The brushes 6 b have in circuit with. them-the auxiliary winding 05 and the transformer secondary winding 0. A movable contact cl is included in these connections, so that the amount oft-he secondary winding 0 in the circuit may be varied. The voltage induced in the auxiliary winding 0, is in phase with the voltage impressed on the inducing winding -A and, consequently, in phase with the voltage of the secondary winding 0.

The advantage of employing the auxiliary winding a in combination withthe auxiliary transformer winding 0 is, first, that the starting torque of the motor is increased, since the current induced in the rotor winding between brushes 5' by the inducing winding at starting flows through the aux iliary winding a and this current in the rotor Winding and in the auxiliary winding a produces a torque which assists in starting the motor, and, in the second place, the use of the transformer winding (2 in circuit with the auxiliary winding 0; makes it unnecessary to bring out a number of leads from the auxiliary winding. The windings a, and '0' together impress on the brushes 6" a voltage which increases the power factor of the motor. If the contact d is moved at the same time that contact at is moved, the power factor may be maintained at its maximum value for all speeds. At speedsbelow synchronism the voltages of windings too ' windings and c arein opposition.

a. and c are iii series; near synchronism,

'when the brushes b b are short-circuited,

these brushes. It will be noted that thevoltages brushes 6 5 through the contacts d and d dependently of the motor current.

' In order that the power factor may be regulated properly for all speeds, Icontrol the contacts d d by a single switch member shown at D in Fig. 2. Contact d, shown in dotted lines, moves over an arc-shaped'contact E connected to the left-hand brush and right-hand 'terminal'of inducing winding A, and over a series of contacts 6 con nected to points on th secondary winding C. Contact d mov over an arc-shape contact E connectedto the upper brush b points on the secondaryw'inding 0.

I do not desire to limit myself to the par ticular constructions and arrangement of parts shown and described, but aim in the appended claims to cover all modifications which are within the scope of my invention.'

. What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A single phase motor of the commutator type having an induc stator, connections forming with the rotor winding a circuit in inductive relation to said inducingwinding, a source of variable voltage included in said circuit, a second set of connections establishing" a circuit through the rotor .winding displaced approximately 90 electrical degrees from the first mentioned rotor circuit,- an auxiliary winding on the stator in .inductive.relation to the inducing winding included in said second circuit, and a source of voltage external to the motor also included in said second circuit, said voltage being in phasewith the voltage at the motor terminals and va riable independently of themotor current.

2." A single phase motonot' the commutator type having an inducing winding on the stator, a set of commutator brushes vdisplaced bya smallangle from the line of inag'netization of said inducing winding, a

source of variable voltage connected to said brushes, asecond set of brushes displaced] approximately 90 electrical degrees from the set, an auxiliary Winding on the stator "impressed on the brushes Z) Z) and onthe and over a series of contacts 6 connected to ing winding on thev in inductive relation to said inducing winding connected in series with said second set of brushes, and a source of variable voltage external to the motor in series with said auxiliary winding and second set of brushes.

3. A single phase motor of the commutator type having an inducing winding on the stator, connections forming with the rotor Winding a circuit in inductive relation to said inducing winding, a source of variable and reversible voltage included in said cir-. cuit,. a second set of connections establishing a circuit through. the rotor winding displaced approximately 90 electrical degrees from the first mentioned rotor circuit, an auxiliary winding on the stator in inductive relation to the inducing winding included in said second circuit, and a source ofvariable and reversiblevoltage external to the motor also included in said second circuit.

4. A single phase motor of the commutator type having an inducing winding on the stator, a set of commutator brushes dis placed by a small angle from the line of E'- magnetization of said inducing winding, a

source of variable and reversible voltage connected to said brushes, a second set of. brushes displaced approximately 90 electrical degrees from the first set, an auxiliary windin on the stator. in inductive relation to said inducing winding connected inserles with said second set of brushes, and a souice of variable and reversible voltage external to the motor iii-series with said auxiliary winding and second set of brushes.

- 5.. A single phase motor of the eomm'utator type having an inducing winding on the stator, a set otcommutat'or brushes dis:

placedby a small angle from the line of magnetization of said inducing winding, a source of'vai'iable voltage connected to said' brushes, a. second set of brushes displaced approximately 9 electrical degrees from the first set, an auxiliary winding onthe stator in inductics-rel'ation to said inducing winding connected in series v of brushes, and a source of voltage external to the motor inv series with said auxiliary winding and said second set of brushes, said voltage-being in phase with the voltage at with said second set the motor terniinals and variable independently of the mdtor current. I

6. A single phase motor of the cor'nmuta tor type having an inducing winding on the stator, connections forming with, the -rotor' winding a circuit in inductive relation to said inducing :winding, 21. second set of connections establishing a circuit through the rotor displaced approximately90 electrical.

degrees from the firstmentioned rotor circuit, sources of variable and'reversible ou n the two rotor clrcuits re age included spectively, and a switch for controlling saidvoltages simu1taneously.-

7L-A single phasp motorof the commute tor type having an inducing Winding on the stator, connections forming With-the rotor; winding .a circuit in inductive relation to said'inducing winding, a source of variable 5 voltage included in said circuit, a second set of connections establishing a circuit through the rotor Winding displaced approximately 90 electrical degrees from the first mentioned rotor circuit an auxiliary winding 0 on the stator in inductive relation to the in- 'ducing winding included in said second cir wit, a source of variable voltage external 'to the motor also included. in said second circuit, said voltage being in phase with the voltage at the motor terminals and varlable independently of the motor current, and a switch for varying simultaneously the volt- 

